If you "liked" the SuppVersity on Facebook (www.facebook.com/SuppVersity) you will probably already have seen the controversies and questions my post "Scientists on the Quest for the Perfect Frying Oil" (read more) has triggered. Eventually, it all revolves about yet another of those nutritional wisdoms that's circulating on the Internet: "Ghee,
tallow, lard, ... saturated animal fats and the coconut micacle, of
course, are the best and only frying oils you should use." (next best Internet source)

How on earth could F. Aladedunye, and R. Przybylski, the authors of the
previously cited study even dare stating that high-oleic low-linolenic rapeseed, high-oleic sunflower oils are good frying oils?

But enough of the sarcasm: In today's installment of "True or False" (read previous installments) we will focus solely on the cholesterol-containing animal fats, and save the one and only "coconut miracle" (Coconut oil - virgin, of course - must be good for everything, right? There have after all (E)-Books been written about it ;-) for another installment of this series.
So, where do we start then? I guess, we could start by rendering down a
big packet of butter in my frying pan... but *wtf* what's that? It's
turning tar black!? Can that really be the ideal frying fat? Probably
not, but if regular butter sucks, what about clarified butter aka
"ghee", then? It's easier to process and there are not tarry clouds
floating in the pan, when you heat it.

"But don't we all know that cholestrol ain't bad for us?"

Unfortunately, there are other problems with ghee; problems that are
related to the heat-induced oxidation of cholesterol and the presence of
large amounts of cholesterol oxides in commercially available
"clarified butter" even before you even start heating it as it was reported by Kubow et al. in 1993 (12.3% w/w of total sterols).

If rancid fish full of oxidized PUFA ain't bad for us (read previous article),
why would we want to use saturated animal fats for frying then? Please
note that the overwhelming evidence says that oxidize PUFAs are bad for
you.

Not a problem? We all know the whole cholesterol thing is a hoax that
was made up just to put everyone on statins? Well, even if that were
the case, the "whole cholesterol thing" is about the effects of intact,
not oxidized cholesterol on heart health. The oxidized sterols in your
"healthy" clarified butter, on the other hand, don't just make it into
the bloodstream (Staprans. 1994 & 2003), they will also be
incorporated in various tissues (Vine. 1997) and lead to a rapid (+100%)
increase the formation of fatty streak lesions in the aorta of lab
animals (Staprans. 2000) and have been linked to the unexplained high
risk of atherosclerosis in Indian immigrant populations in the US
(Jacobson. 1987) as well as the occurrence and progression of
atherosclerosis in general (Leonarduzzi. 2002; Gargiulo. 2011).

As mentioned before, butter is unfortunately, not the only high
cholesterol item on the Internet's list of "best, because highly
saturated, frying oils". Next to butter (215mg of cholesterol / 100g)
you will also find lard (95mg of cholesterol / 100mg) or tallow (109mg
of cholesterol / 100mg) on these lists.

"I always pour away the oil! I am safe, right?" If I had not heard this argument before I would certainly not mention that the oxidized cholesterol do
make it into the fried products. In a study from 1991, Zhang et al.
report that the average content of the measured forms of oxidized
cholesterol in french fries that had been fried in fresh, previously
unoxidized tallow at a fast food restaurant ranged from 1.6-3.8 mg/100g
and thus 3-8x more than Pie et al. found in a rare steak (>0.5mg
/100g after 3 minutes of cooking) or cooked pork (>0.56mg /100g) in
1991 or those reported by Al-Saghir et al. for cooked farmed salmon
(0.33-0.9mg/100g; cf. Al-Saghir. 2004 -- the table on the left is a
fully referenced overview of COP levels in various foods from
Otaegui-Arrazola. 2010).

Needless to say that neither tallow nor lard or any other of these
animal fats contain enough antioxidants to protect their cholesterol
from being oxidized (Ryan. 1981; Park. 1986a,b).

Figure 1: Even if
you believed that cholesterol was bad for you, the ~50% reduction in
intact cholesterol that occurs, when you heat tallow at temperatures of
155°C and 190°C should not be a reason to celebrate (Park. 1986a)

Interestingly, Park et al. have been able to show that this process
starts at temperatures as low as 135°C (the recommended frying
temperature for most products is 160°C+) and does not increase
with higher temperatures. For pure cholesterol Osada et al. determined
120°C as the lowest temperature that induces oxidative changes (Osada.
1993).

In 1986, a group of researchers who conducted research for the French
government found that 78% of the total cholesterol that was lost (23% of
total cholesterol) from beef tallow during deep frying was recovered in
form of the four best known forms of oxidized cholesterol, i.e. Triol-,
7a-, 7/3-, and 7-Oxo-cholesterol (Bascoul. 1986).

Aside from their previously mentioned effect on the progression of atherosclerosis
and their direct effect no the gut lining and other protective barriers
in your body. These cholesterol oxidation products (COPs) have also
been shown to promote the growth of colon (Kendall. 1992) and other
forms of cancer (Sevanian. 1986; Gabitova. 2014), figure in the development of type II diabetes (Mol. 1997), block the production and blood pressure lowering effects of nitric oxide (Brown. 1999) and have been implicated in the development and progression of Alzheimer's disease (AD) and vascular dementia, as well as kidney failure (Sottero. 2009)

Surprising interactions between frying oils and fried foods: I already mentioned that (a) oxidized cholesterol from frying oils migrate into the fried foods, and (b) the cholesterol in
the foods is oxidized, as well. Now, the previously cited study by
Al-Saghir et al. (2004) happened to compare the amount of oxidized
cholesterol (COPs) in cooked farmed salmon for different cooking oils and found that the salmon that had been fried in partially hydrogenated vegetable oils had the lowest, the steamed salmon the highest
content of oxidized cholesterol (0.98mg/100g) - luckily, frying with
olive oil can protect you from both, the transfats in partially
hydrogenated veg. oils and the COPs in steamed salmon.

And while all the non-enzymatically produced COPs in fried (and
other) foods are "bad guys", the enzymatic conversion of cholesterol in
the body (see Figure 2, bottom) can produce compounds of which Otaegui-Arrazola, Menéndez-Carreño, and Ansorena write in their 2010 review that they play
important biological role.

Figure 2: Not all
oxysterols are created equal. Those your body creates by enzymatic
reactions figure in cholesterol homeostasis (Otaegui-Arrazola. 2010)

In fact, certain oxysterols can suppress the activation of the master
transcriptional regulators of lipid homeostasis (SREBPs) by binding to
an oxysterol sensing protein in the Endoplasmic Reticulum, while others
accelerate the degradation of the key cholesterol biosynthetic enzyme,
HMG-CoA reductase, and/or serve as natural ligand activators of a
nuclear receptor (LXR) involved in coordinating many aspects of reverse
cholesterol transport (Gill. 2008).

These "good oxysterols" do thus appear(!) to play a subtle but
important role in the control of cholesterol homeostasis. In the context
of this true or false question, their existence, functions and benefits
are however irrelevant. Apropos, question! What's the answer to our
question, after all?

The best advice I can give you is to stop consuming fried foods.

We may not be able to trace obesity, diabetes, heart disease, cancer and
dementia back to a specific frying oil - what we can do, though, is to
draw the links between these and the general consumption of fried foods.

Note: You may or may not have realized this, but at least with
respect to the formation of oxidized cholesterol products, the "healthy"
steaming turned out to be even worse than frying in Al-Saghir's 2004
study (see light-blue infobox)

Are butter, ghee, lard & tallow the best or the worst frying fats? While it stands out of question that the cholesterol oxidation products (COPs) are bad for you, we don't have a study that proves
that the amount you'd consume if you were frying your eggs in butter in
the morning will cause all sorts of ailments from "A" as "Alzheimer's"
to "Z" as in "diabeteZ" ;-)

The previously cited animal studies have - as usual - been conducted
with very high amounts of oxidized cholesterol in the diet and the "Ghee
is the reason for increased heart disease in British Indians"
hypothesis Jacobson et al. proposed in their 1982 article in The Lancet would
not explain, why Indians who live in India didn't have a similarly high
heart disease risk at that time... that being said, from 1960 to 1995
the prevalence of heart disease in urban areas of India increased from a
meager 1% to almost 10% (Gupta. 1995; compare that to "only" 8.7% in US
citizens aged 50years or older; Alexander. 2003). Moreover, US Indians
who use >1kg of ghee to fry their foods have a record-breaking 4x
increase in atherosclerosis risk compared to their non-ghee eating peers
(Gupta. 1997).

You see, we can go back and forth on this and still won't make any progress. Personally, I would not
use ghee, tallow or lard for frying; and whether coconut oil, or maybe
olive oil, of which you know that it is cholesterol-free and learned
that it reduces the rate of cholesterol oxidation (Al-Saghir. 2004) are
better alternatives is going to be a topic for another installment of True or False - so stay tuned for more!